Assessing the efficiency and microbial diversity of H2S-removing biotrickling filters at various pH conditions.

This study aimed to investigate the operation of three parallel biotrickling filters (BTFs) in removing H2S at different pH conditions (haloalkaliphilic, neutrophilic, and acidophilic) and their associated microbial population in the biodesulfurization process. BTF columns were inoculated with enriched inoculum and experiments were performed by gradually reducing Empty Bed Retention Time (EBRT) and increasing inlet concentration in which the maximum removal efficiency and maximum elimination capacity in EBRT 60 s reached their maximum level in haloalkaline condition (91% and 179.5 g S-H2S m-3 h-1). For visualizing the attached microbial biofilms on pall rings, Scanning Electron Microscopy (SEM) was used and microbial community structure analysis by NGS showed that the most abundant phyla in haBTF, nBTF, and aBTF belong to Gammaproteobacteria, Betaproteobacteria, and Acidithiobacillia, respectively. Shannon and Simpson indexes evaluation showed a lower diversity of bacteria in the aBTF reactor than that of nBTF and haBTF and beta analysis indicated a different composition of bacteria in haBTF compared to the other two filters. These results indicated that the proper performance of BTF under haloalkaliphilic conditions is the most effective way for H2S removal from air pollutants of different industries.

Acceleration a yeast-based biodegradation process of polyethylene terephthalate microplastics by Tween 20: Efficiency, by-product analysis, and metabolic pathway Prediction.

Polyethylene terephthalate is a widely produced plastic polymer that exhibits considerable biodegradation resistance, making its derived microplastics ubiquitous environmental pollutants. In this study, a new yeast strain (Vanrija sp. SlgEBL5) was isolated and found to have lipase and esterase-positive capabilities for degrading polyethylene terephthalate microplastics. This isolate changed the microplastic surface charge from -19.3 to +31.0 mV and reduced more than 150 µm of its size in addition to reducing the intensity of the terephthalate, methylene, and ester bond functional groups of the polymer in 30 days. Tween 20 as a chemical auxiliary treatment combined with biodegradation increased the microplastic degradation rate from 10 to 16.6% and the thermal degradation rate from 85 to 89%. Releasing less potentially hazardous by-products like 1,2 diethyl-benzene despite the higher abundance of long-chain n-alkanes, including octadecane and tetracosane was also the result of the bio + chemical treatment. Altogether, the findings showed that Vanrija sp. SlgEBL5 has the potential as a biological treating agent for polyethylene terephthalate microplastics, and the simultaneous bio + chemical treatment enhanced the biodegradation rate and efficiency.

Aerobic biodegradation of untreated polyester-polyether urethanes by newly isolated yeast strains Exophilia sp. NS-7 and Rhodotorula sp. NS-12.

Polyester-urethanes as the most widely used polyurethanes (PUs) are among the most recalcitrant plastics in natural conditions. Among existing approaches for managing and reducing plastic waste, biodegradation as a promising approach to reduce plastic waste pollution has drawn scientific society's attention in recent years. In this study, two polyester-polyether urethane degrading yeasts were isolated and identified as two new strains of Exophilia sp. NS-7 and Rhodotorula sp. NS-12. The results showed that Exophilia sp. NS-7 is esterase, protease, and urease positive, and Rhodotorula sp. NS-12 can produce esterase and urease. Both strains can degrade Impranil® as the sole carbon source with the highest growth rate in 4-6 and 8-12 days, respectively. SEM micrograph revealed PU degradation ability in both strains by showing so many pits and holes in treated films. The Sturm test showed that these two isolates can mineralize PU to CO2, and significant decreases in N-H stretching, C-H stretching, C=O stretching, and N-H/C=O bending absorption in the molecular structure of PU were revealed by the FT-IR spectrum. The detection of the deshielding effect in chemical shifts of the H-NMR spectrum after the treatment also confirmed the destructive effects of both strains on PU films.